1. Field of the Invention
The present invention relates to an emission control driver having a simple circuit for generating an emission control signal, and an organic light emitting display (OLED) having the same.
2. Discussion of the Background
Where an emission control transistor for controlling the emission of a light emitting device is added to a pixel circuit, an emission control driver must transmit an emission control signal to the emission control transistor.
A conventional emission control driver has been separately fabricated and mounted to a substrate with a pixel portion by a tape carrier package (TCP) or similar method in a subsequent manufacturing step. Thus, the additional step lowers production yield, complicates the fabrication process, and increases production cost. To solve these problems, an OLED with an emission control driver integrated into a panel has been developed.
FIG. 1 shows the configuration of a conventional OLED having an emission control driver integrated into a panel.
Referring to FIG. 1, the OLED includes a scan driver 400, a data driver 500, and a panel 100. Further, the panel 100 includes a pixel portion 300, and an emission control driver 200.
The pixel portion 300 includes pixel circuits 310 that are connected to scan lines S1 through Sn, data lines D1 through Dm and emission control lines E1 though En. The pixel circuits 310 are arranged in a matrix form and display a predetermined image.
The scan driver 400 sequentially supplies scan signals to scan lines S1 through Sn formed in the pixel portion 300.
The data driver 500 supplies a predetermined data signal to data lines D1 through Dn formed in the pixel portion 300.
The emission control driver 200 supplies an emission control signal to emission control lines E1 through En formed in the pixel portion 300, thereby controlling an emission operation of the pixel portion 300.
The pixel portion 300 and the emission control driver 200 are integrated in the panel 100. Specifically, a thin film transistor (TFT) array for driving pixels and an emission control circuit 210 of the emission control driver 200 are integrated into the panel 100.
Generally, the TFT used as a switching device in the pixel portion 300 uses poly-silicon with high mobility to form a channel. In the emission control driver 200, a transistor used as the switching device must also have a fast response time, so the poly-silicon with high mobility can effectively form the channel.
Therefore, the emission control circuit 210 of the emission control driver 200 and the pixel-driving transistor could be made of the same silicon, and a switching transistor with fast response time would be formed in a simplified fabrication process since there would be no need to connect the pixel portion 300 with the emission control driver 200.
However, the conventional emission control driver 200 is not composed of only a p-type metal oxide semiconductor field effect transistor (MOSFET), which is usually used in the pixel portion 300. Therefore, it would not be possible to fabricate the emission control driver 200 and the transistor of the pixel portion 300 in the same process.
Additionally, where the emission control driver 200 has been composed of a shift register, many control signals, such as CLK or CLKB, are required to drive the shift register. However, such control signals are applied from an external controller, so the layout becomes complicated. Furthermore, the external controller results in additional power consumption by the panel.